Penulis Maruli Harry Siregar David P. E. Saerang DOI: https://doi.org/10.32400/gc.10.1.7366.2015 Abstrak Unduhan PDF (English) Diterbitkan 2015-03-31 Terbitan Vol 10 No 1 (2015) Bagian Articles Lisensi Author keep the copyright of the article published in this journal